The field of devices of the inventions are those designed for preventing jackknifing between a truck and trailer and the method of operation of the system.
Jackknifing has been ranked as the third most hazardous type of truck accident, accounting in the United States of America for approximately $20,000,000 of property damage and more than 5% of the fatal truck-trailer accidents. Safe driving practices such as keeping speed down to a safe speed for road conditions, avoidance of sudden decelerations and slippery surfaces or loose dirt, safe easy stops and smooth steering substantially improve the risk of a jackknife occurrence. Nevertheless the jackknife accident continues to occur thousands of times a year.
Trucks pull a trailer through a fifth wheel-kingpin connection which allows the tractor and trailer to pivot about the axis of this connection. The huge tractor rigs on the highway are guided by the small front tire footprint on the road. When braking, even at slow speeds, the inertia forces push at an angle against the pivot point connection and the trailer swings around pulling the tractor out of position, breaking the front tire contact, and causing a complete loss of control and a "jackknife" occurs as the trailer and tractor pivot on the kingpin connection toward each other to close like a knife blade enters the handle in a camper's jackknife. Uneven braking can trigger the phenomena, as well as side winds, sudden engine deceleration and loss of braking. The trailer can override the tractor pushing it into jackknife or the tractor can underride the trailer and cause the jackknife. These variable causes make a practical solution to the problem difficult.
This problem has long been known. It has been known for at least a decade that corrective action needs to be taken before the angle between a tractor and trailer exceeds 15 degrees. Over the years many "solutions" to this problem have been suggested. In the last decade electrical brakes were suggested as a means to reduce the jackknife occurrence, and these were employed on many trailers. However, this system did not effectively work and few vehicles use this "solution". Since 1975 so called anti-lock systems known as 121 brakes required by U.S. Federal Motor Vehicle Safety Standard 121 have been employed to automatically release brakes on an axle or tandem if any wheel locks up more than momentarily. Still sudden brake applications can cause wheel lock-up. Hand valves to cause trailer wheels to lock to prevent jackknifes have been proposed, but the U.S. National Safety Council found this solution could actually induce trailer jackknifes. Drivers who over-accelerate in a effort to pull out of such an induced jackknife may induce a tractor jackknife by spin-out.
While there are only six fundamental machines the field of mechanisms and structures may be unlimited. However, in this art here have been numerous suggestions in prior art attempts. An effective solution needs to be cost effective and safe and reliable. The many prior art devices suggested by the patent literature are not seen on the vehicles on the road today and jackknife accidents continue to occur. If an effective solution had been achieved, in view of the clear need, one of the prior art devices should have been adopted widely prior to this time. With such a number of prior devices available, without the use of hindsight, a description of relevant background prior art applicable to the present invention would not be readily apparent. In the prior art there does exist many attempts to limit the amount of pivotal movement of the fifth wheel and kingpin of a tractor-semitrailer combination and other various arrangements to prevent or minimize the tendencies of tractor-trailers to jackknife. However, these arrangements do not provide apparatus which are adjustable to road conditions as does the present apparatus and they do not provide a control system for continuous monitoring of an anti-jackknifing apparatus which limits swing to a anti-jackknifing controlling arc and which allow the driver to control the vehicle and control apparatus in accordance with varying road conditions and rig movement and which has the other features which will be described. A representative sample of the prior art granted over many years may be listed as follows:
U.S. Pat. No. 2,462,211, filed Feb. 24, 1947 to C. L. Moore PA1 U.S. Pat. No. 2,553,959, issued May 22, 1951 to H. F. Cook et al. PA1 U.S. Pat. No. 2,652,262, filed Oct. 19, 1950 to W. G. Sherry PA1 U.S. Pat. No. 2,962,301, filed Oct. 15, 1959 and issued November, 1960 to W. J. Leinbach PA1 W. Ger. Pat. No. 960,696 issued Mar. 7, 1957 naming Hans Becker as inventor PA1 U.S. Pat. No. 3,031,205, issued Apr. 24, 1962 to P. Fox PA1 U.S. Pat. No. 3,063,739, issued Nov. 13, 1962 to P. M. Davies PA1 U.S. Pat. No. 3,420,548, filed Oct. 7, 1966 to C. M Wakeman PA1 U.S. Pat. No. 3,588,809, issued June 28, 1971 to A. S. Devlin PA1 U.S. Pat. No. 3,774,941, filed Feb. 14, 1972 to H. H. Durr PA1 U.S. Pat. No. 3,837,678, filed May 3, 1973 and issued September, 1974 to R. Cicero PA1 U.S. Pat. No. 3,856,329, issued Dec. 24, 1974 to M. A. Ordorica PA1 U.S. Pat. No. 3,895,827, issued July 22, 1975 to J. D. Padrick PA1 U.S. Pat. No. 3,972,542, issued Aug. 3, 1976 to Arthur A. Dirks PA1 U.S. Pat. No. 4,040,006, issued Aug. 2, 1977 to R. W. Kimmel PA1 U.S. Pat. No. 4,068,860, issued Jan. 17, 1978 to A. Dirks and W. Meyers PA1 U.S. Pat. No. 4,556,232 issued Dec. 3, 1985 to J. I. Sever
Such a hindsight collection of patents can be developed after a review of the inventions herein. Prior art warning devices exist which warn drives of an oncoming jackknife, and which indicate fishtailing, principally relating to vehicles which do not employ a fifth wheel. A number of recognized prior art inventions recognized by their patents have disclosed the positioning of a device, such as a block or abutment member, within guide lugs in the entranceway or V-slot of the slide plate of a fifth wheel mounted on the tractor to prevent jackknifing. However, these inventions have not been widely adopted. Representative examples include U.S. Pat. Nos. 2,553,959; 2,962,301; 3,972,542 and 4,068,860. In the U.S. Patents to Dirks et al., this concept was employed and implemented by a generally horizontal longitudinally extending restraining tongue rigidly mounted on the trailer underside and terminating as a forward tapered tongue tip (or bracket) between the lugs in an extended station position. A remotely controlled cylinder attached to the tongue caused horizontal tongue reciptocation between the retracted and forward extending position to prevent jackknifes. After a review of the detailed description below it will be appreciated that none of the prior art attempts accomplish the results of the present inventions as detailed in the description.